Plasticized cellulose derivatives



2,809,899 PLASTICIZED CELLULDSE, DE IVATIVES John Di Brandner, Arden, Company, Wilmington, ware Dli, assignor to Atlas jPowder DeL, a corporation o'f-Dela- No Drawing. Original application April 25, 1950, Serial No. 158,090, now PatentNo; 2,715,139, dated August 9, 195 5. Divided and this application March 24, 1955, Serial No'. 496,590

6 Claims. (Cl. 106-179) This application is' a division of mycop'ending applica' tion Serial No. 158,090, filed April 25, 1950, now U. S. Patent No. 2,715,139 and relates particularly 'to' plasticiz'ed compositions of cellulosederivatives.

Derivatives of cellulose" constitute" anirnportant class of synthetic plastics and find wide application in such diverse forms as yarns, sheets and wrappingfoils, films for supporting photographic emulsions, lacquersand' other coating compositions, molded objects, extruded forms, and the like. In most of such applications it -is-necessary that there be incorporated with thercellulose ester 3. plasticizing ingredient to impart flexibility, or toughness, or to improve the impact strength, or otherwiseproperties of the completed article.

It is an object of this invention to providenew organic esters.

esters which are plasticizers for cellulose derivatives.

Another object is to provide new plasticiz'ed compositions of cellulose derivatives.

Other objects will become apparent in thecou'rseof the following description and the appendedclaims,

'Iheno'v'el plasticizers of the" present invention comprise diesters of diglycolic acid which conf ormto the formula R morocco) B1 in which R is a radical selected from the group consisting of CHa ifil) a wherein x is 1 or 2,.nt'is ajwho lenumberj fro'mgfito 4, n is a whole numberfr'om' 0t'o'2, and the"sumofm n is from 1 to 4; and R is a radical selected-from-the "group consisting of a a and Ro ina- I and be listed asr il ltfstfative It is a more particular object to-pro'vide new organic 2,809,899 Patented Oct. 15, 1957 ice Di-(phenoxy triethoxy ethyl) diglycolate' Di-(phenoxy diethoxy propyl) diglycolate (Phenoxy ethoxy ethyl) (phenoxy diethoxy ethyl) diglycolate Plasticizing esters of the type above defined and exemplified may be readily prepared by' direct esterification of diglycolic acid with one or more ether-alcohols represented by the: formulas ROH and R OH" where R and R have the meanings above ascribed thereto. The said ether-alcohols may be purified single chemical identities or, equally satisfactorily, may be mixtures of lower oxydesirable modify the defined by the above generic alkylated phenols or cresols' obtained by. the direct addition of the appropriate-alkylene oxide to phenol or cresol. In referring to ether-alcohols so prepared" and their radicals, the indicated number ofoxyalkylene groups in the compound designates the average number of such groups as determined by the numberof mols of oxide reacted per mol of phenolic compound. Thus the expression phenoxy ethoxy ethanol refers equally, for purposes of. this speci fication, to the compound O-oomcrnoomornon and to the mixtureof ether alcohols resulting from the addition of two mols of-ethylene oxide to one mol of phenol. Methods of preparing such etheral-cohols are well known and need not-be elaborated here.

Equally, within the purview of the invention are diglycolic diesters of mixtures of polyolefi'n glycol ethers of phenol and/or cresol wherein the average number of olefin oxide groups per mol of said phenol or cresol is not a small whole number but is any fractional number within the limits indicated inthe primary definition above. It will be recognizedthatsuch compositions will comprise mixtures of compounds each conforming to the generic definition above, and mixtures of such compounds are the .full equivalent-of the compounds singly. These' and other modifications which do not depart from the spirit of theinvention will be obvious to those skilled in the art.

Alternatively the plasticizing esters of the present invention may be made by other conventional means such, for example, as by reaction between diglycolic anhydride andthe appropriate ether-alcohols, or between diglycolyl chlorideiand the appropriate ether-alcohols in the presence of an acid acceptor, or by alcoholysi's of lower alkyl diglycolates withthe desired ether-alcohol or mixture of ether-alcohols. Esters'conforming to the'generic formula above, andcompo'sition's containing such esters as. defined hereinafter, are the subject of the present invention, whether the esters be prepared by any of the above indicated procedures for by otherequivalentmethods.

..The cellulose derivative'component of the novel plasticized compositions of the present invention is selected from the group consisting of cellulose nitrate, lower fatty acid esters of cellulose, and lower alkyl ethers of cellulose. Exemplifyingqsuc'h derivatives are ethyl-cellulose, cellulose nitrate, cellulose acetate, cellulose propionate, and cellulose. esters. of mixed lower fatty acids, such as cellulose aceto-biityrate and the like: The new plasticizers are of particular advantage in cellulose acetate compositions and especially in cellulose acetate films. In many cases they may serve as the sole plasticizing ingredient although theyare compatible with other known plasticizers for the cellulose esters and may be used in conjunction therewith. For example, suitable combination plasticizers are mixtures of the diglycolic diesters of the present invention and lower alkyl phthalates, low'er-"alkylphthalyl ethyl glycolates, triphenyl or tricresylphosphate; and the like.

Also as is well understood in theart, the-proportion of total plasticizer tocellulos'e derivative in usteiul compositions will vary-greatly-with the use to which the composition is to be put, as well as with the specific plasticizer or plasticizer combination employed. In general, however, it is preferred to employ at least 10 parts and not more than 50 parts by weight of total plasticizer per 100 parts of cellulose derivative to obtain sufiicient plasticizing efiect and yet not unduly weaken the composition by dilution of the cellulose derivative. Of the total plasticizer so employed, at least 25 percent, and any greater proportion up to 100% should comprise the novel diesters of diglycolic acid hereinbefore defined.

Suitable combination plasticizers containing at least 25% of the diesters of the present invention are tabulated below.

Prior Art Plasticizer Novel Plastieizer 75% butyl phthalyl ethyl glycolate 60% diethyl phthalate 50% dimethyl phthalate 25% tricresyl phosphate The ester plasticizers of the present invention are unusually resistant to hydrolysis and cellulose ester compositions plasticized with mixtures containing a high proportion thereof are highly resistant to leaching by water. Moreover, such cellulose ester compositions do not suffer undue loss of plasticizer by volatilization on warm storage and are exceptionally resistant to deterioration by ultraviolet light. In film form they exhibit excellent tensile and tear strength, high folding endurance, transparency, and freedom from color. Moldings of compositions so plasticized are tough, of high impact strength, and of low water absorption.

It has been pointed out hereinbefore that the novel esters of the present invention may be prepared by any of a number of known procedures. A convenient method is to form the said esters by direct esterification between diglycolic acid and an excess of the chosen aryl-aliphatic ether-alcohol and subsequently remove the excess alcohol by distillation. The reaction mixture is first heated in an inert atmosphere and under substantially atmospheric pressure in a vessel equipped with a short fractionating column, the temperature at the head of the column being regulated to reflux substantially all of the ether-alcohol while removing water. When the acid number of the charge reaches a selected low value, preferably under 15, vacuum is applied to the system and the rate of heating increased to remove by distillation the unreacted excess of ether-alcohol. The formed ester may be conveniently treated with a decolorizing agent such as activated carbon or the like, and filtered while still warm it it is desired to obtain an ester of light color.

Within the framework of the above general description the following specific examples illustrate the preparation of esters in accordance with the present invention in more detail.

EXAMPLE I Diglycolic acid ester of phenoxy ethoxy ethanol Charge:

546 grams (3 mols) phenoxyethoxy ethanol 134 grams (1 mol) diglycolic acid Esterification step:

Time: 5 hours Pot temperature: Rising from 140 to 230 C. Column temperature: 100 C. Acid number of charge at end: 6

Distillation step:

Time: 1.5 hours Pot temperature: 230 C. Column temperature: 190 C. max. Pressure: 3 mm. mercury absolute Recovered phenoxyethoxy ethanol: 162 grams 4 Decolorizing step:

Temperature: 140 C. Activated carbon: 0.5% of original charge Time: 15 min. Filtration temperature: 75 C.

Final product:

Yield: 462 grams Form: Pale yellow moderately viscous liquid Acid No.=4 Hydroxyl No.=5 Saponification No.=234

EXAMPLE II Diglycolic acid ester of phenoxy propanol Charge:

304 grams (2 mols) phenoxy propanol 107 grams (.8 mol) diglycolic acid Esterification step:

Time. 12 hours Pot temperature 140 to 220 C. Column temperature: C. Acid number of charge at end: 11

Distillation step:

Time: 1 hour Pot temperature: 210 C. Column temperature: 156 C. maximum Pressure: 2 mm. mercury absolute Ether-alcohol recovered: 55 grams Decolorizing step:

Temperature: C. Activated carbon: 0.5 of original charge Time: 15 min. Filtration temperature: 75 C.

EXAMPLE III Diglycolic acid ester of mixed cresoxyethanols Charge:

228 grams (1.5 mols) o-cresoxyethanol 228 grams (1.5 mols) m-cresoxyethanol 134 grams (1 mol) diglycolic acid Esterification step:

Time: 6 hours Pot temperature: 140 to 200 C. Column temperature: 100 C. Acid number of charge at end: 11

Distillation step:

Time: 2 hours Pot temperature: 200 C. Column temperature: C. maximum Pressure: 2 mm. mercury absolute Recovered mixed cresoxyethanols: 134 grams Decolorizing step:

Temperature: 140 C. Activated carbon: 0.5 of original charge Time: 15 min. Filtration temperature: 75 C.

Final product:

Yield: 388 grams Form: Yellow moderately viscous liquid Acid No.: 7 Hydroxyl No.: 7 Saponification No.: 276

annexes EXAMPLE :I] Diglycolic acid ester of phenoxy triethoxy ethanol Charge:

540 grams (2 mols) of'the etheralco'hol obtained by the direct addition of 4 mols of ethylene oxide to 1 mol of phenol 121 grams-(.9 mol) diglycolicacid Esterification step:

Time: 6'hours 1 Pot'temperature: 140-230 "C. Columntemperature: 100C. Acid No. at'end: 16 Distillation step:

Time: 1.5 hours Pottemperature: 250C. (main) Column temperature: 190 C. max. Pressure: 2 mm. mercury absolute Recovered ether-alcohol: 55 grams Decolorizing step: Temperature: 140C. Activated carbon: 0.5 Time: min. Filtration temperature: 75 C. Final'product:

Yield: 555 grams Form: Deep yellow moderately viscous liquid Acid'numberz l Hydroxyl number: 11 Saponification number: 169

The following examples are illustrative of cellulose derivative compositions plasticized 'with the novel plasticizers of the present invention. vAll'inclicated parts are by weight.

. EXAMPLE V Cellulose acetate film 18 partsof cellulose acetate having an acetic acid content of 55.6 to 55 seconds were dissolved in a mixed solvent consisting of:

20 parts methyl ethyl ketone 13 parts ethyl acetate 19 parts dioxane parts acetone and pressure filtered to form a base solution.

9 parts of the product of Example I were dissolved in 100 parts of the base solution to yield a solution of a of original charge I plasticized cellulose acetate suitable for film formation.

A film of 0.045" wet thickness was cast on glass from the above solution, conditioned in a solvent atmosphere over night, and air dried for 4 hours. The film was then stripped from the glass and conditioned for 48 hours at room temperature. The resulting film was, very flexible and transparent, exhibited high elongation'before finally rupturing in tensile strength test, and showed excellent resistance to deterioration and discoloration under ultraviolet light. It underwent remarkably little loss by volatilization at 85 C. and low loss by solution on immersion in cold water for 16 hours.

EXAMPLE VI The process of Example V was repeated except that 9 parts of the same plasticizer was dissolved in 200 parts of the base solution. The resulting film was somewhat tougher than that of Example V exhibiting less elongation and greater tensile strength. Itwas colorless, transparent 5612 percent and a viscosity of to' and flexible, very resistant to deterioration by ultraviolet light and withstood very satisfactorily the tests for solubility in cold water and loss by volatilization.

EXAMPLE VII The product of Example IV was substituted for the product of Example I in the process described in Example VI. The resulting was very similar in properties to "that of {the film of Example VI being slightly more resistant to loss by volatilization and slightly less resistant to loss by leaching in cold water.

EXAMPLE VIII The product of Example III was substituted for that :of Example I in the film casting solution of ExampleVl. Theresultingfilmwas clear, flexible, and strong, unusually resistant to cold water extraction, and excellent in respect .to loss by volatiliza'tion.

EXAMPLE IX The :productof Example II was .substitutedfor that of ,Examplel in the film casting solution of Example V. The resulting ,film was clear, very flexible, and strong. Its resistance tocold waterleaching was excellent and its loss by volatilization was quite good.

EXAMPLE X Plasticized ethyl cellulose film.-A base solution was prepared from 35 parts of 50 centipoises ethyl cellulose in 65 parts of a mixed solvent composed of:

in 100 parts of the base solution and a film cast from the resulting mixture according to the technique of Example V. There was obtained a clear film of good tensile 'strengthandelongation.

EXAMPLE XI Plasticized cellulose acetate-butyrate film..Prepare a base solution by dissolving 20 parts of cellulose acetate butyrate, characterized by a viscosity of 17-33 seconds,

an average acetyl content of 13% and average butyryl content of 37%, in parts of 'a solvent composed of:

Parts Acetone 20 Cyclohexanone 30 Ethyl acetate 20 Ethyl lactate 5 Dioxane 5 Dissolve 5 parts of the product of Example I in parts of the said base solution and cast films therefrom according to the technique of Example V. The resulting films are transparent, flexible, tough and of excellent physical characteristics.

EXAMPLE XII Plaslicized cellulose nitrate film.Prepare a base solution by dissolving 19.5 parts of half second nitrocellulose in 70.5 parts of a mixed solvent composed of:

Parts Butyl alcohol 10.5 Butyl acetate 2O Ethyl acetate 20 Toluol 30 Dissolve 3.9 grams of the product of Example I in 100 grams of the said base solution and cast a film therefrom according to the technique of Example V. The resulting film is transparent, flexible, and of excellent physical properties.

EXAMPLE XIII 7 was introduced into a disk mold and compression molded at 430-440 F. for 15 minutes at SO'OO lbs. per square inch. The resulting disk was clear, very light in color, tough, strong and of low water absorption The above examples are illustrative only and many variations therefrom which do not'depart from the spirit of the invention will be readily recognizedby those skilled in the art. Equally within the scope of the invention are compositions of cellulose derivatives, comprising the novel plasticizers herein disclosed, and containing added ingredients, such, for example, as dyes, pigments, fillers and modifying resins.

What is claimed is:

1. A plasticized composition comprising a cellulose derivative selected from the group consisting of cellulose nitrate, cellulose esters of lower fatty acids, and lower alkyl ethers of cellulose and a plasticizer therefor comprising a diester of diglycolie acid which conforms to the formula wherein x is an integer greater than and less than 3, m is a whole number from 0 to 4, n is a Whole number from O to 2, and the sum of m+n is from 1 to 4; and R is a radical selected from the group consisting of OHS and

and

- 8 wherein x=1 or 2, m is a whole number from 0 to 4, n is a whole number from 0 to 2, the sum of m+n is from 1 to 4, and 2m+3n is at least 3.

2. A plasticized composition as in claim 1 wherein there are present from about 10 to about parts by weight of said plasticizer per parts of said cellulose derivative.

3. A plasticized composition comprising 100 parts by weight of a cellulose derivative selected from the group consisting of cellulose nitrate, cellulose esters of lower fatty acids and lower alkyl ethers of cellulose, and from about 10 parts to about 50 parts by weight of total plasticizer, said plasticizer containing at least 25% by weight of a diester of diglycolic acid as defined in claim 1.

4. A plasticized composition comprising 100 parts by weight of cellulose acetate and from about 10 parts to about 50 parts by weight of di-(phenoxyethoxy ethyl) diglycolate.

5. A plasticized composition comprising 100 parts by weight of cellulose acetate and from about 10 parts to about 50 parts by weight of a mixed plasticizer consisting of 50% by weight dimethyl phthalate and 50% by weight of di-(phenoxyethoxy ethyl) diglycolate.

6. A plasticized composition comprising 100 parts by weight of cellulose acetate and from about 10 parts to about 50 parts by weight of di-(cresoxyethyl) diglycolate.

References Cited in the file of this patent UNITED STATES PATENTS Cellulose Acetate Plastics, Stannett (1950), p. 43.

Ott et al.: High Polymers, vol. V, p. III (1955), p. 1462.

Handbook of Plastics, Simonds and Ellis (1943), pp. 252 to 271. 

1. A PALSTICIZED COMPOSITION COMPRISING A CELLULOSE DERIVATIVE SELECTED FROM THE GROUP CONSISSTING OF CELLULOSE NITRATE, CELULOSE ESTERS OF LOWER FATTY ACIDS, AND LOWER ALKYL ETHERS OF CELLULOSE AND A PLASTICIZER THEREFOR COMPRISING A DIESTER OF DIGLYCOLIC ACID WHICH CONFORMS TO THE FORMULA 